@article{guner_pesic-vanesbroeck_rivera-burgos_wehner_2019, title={Screening for Resistance to Zucchini yellow mosaic virus in the Watermelon Germplasm}, volume={54}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI13325-18}, abstractNote={The Florida strain of Zucchini yellow mosaic virus (ZYMV-FL) is one of the major viral diseases of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. Although some screening has been performed for ZYMV resistance in watermelon, the germplasm collection has not been screened extensively for resistance. The objectives of this study were to screen the U.S. Department of Agriculture (USDA) watermelon germplasm collection for ZYMV resistance and to verify the disease rating for the most resistant and most susceptible accessions. We used a randomized complete block with four replications, 1613 PI accessions, and 41 cultivars. ‘Charleston Gray’ and ‘Crimson Sweet’ susceptible controls were used to verify that the ZYMV inoculum was virulent. After the last rating, an enzyme-linked immunosorbent assay (ELISA) was performed to determine the presence of a virus in the plant tissue. The PI accessions with high resistance to ZYMV-FL that also exhibited resistance to other watermelon viruses were PI 595203, PI 386015, PI 386016, PI 386024, PI 386025, PI 386026, PI 244018, PI 244019, PI 485583, PI 494528, and PI 494529. The ZYMV-FL retest of the most resistant 46 PI accessions showed that there were some escapes. Sixteen resistant PI accessions had a rating of 3.0 or less for the average and maximum ratings: PI 595203, PI 537277, PI 560016, PI 386016, PI 386019, PI 485580, PI 494529, PI 595200, PI 494528, PI 595201, PI 386025, PI 494530, PI 386015, PI 386021, PI 386026, and PI 596662. Overall, PI 595203 had the highest resistance according to both the germplasm screening and the retest studies.}, number={2}, journal={HORTSCIENCE}, author={Guner, Nihat and Pesic-VanEsbroeck, Zvezdana and Rivera-Burgos, Luis A. and Wehner, Todd C.}, year={2019}, month={Feb}, pages={206–211} }
 @article{ling_harris_meyer_levi_guner_wehner_bendahmane_havey_2009, title={Non-synonymous single nucleotide polymorphisms in the watermelon eIF4E gene are closely associated with resistance to Zucchini yellow mosaic virus}, volume={120}, ISSN={["1432-2242"]}, DOI={10.1007/s00122-009-1169-0}, abstractNote={Zucchini yellow mosaic virus (ZYMV) is one of the most economically important potyviruses infecting cucurbit crops worldwide. Using a candidate gene approach, we cloned and sequenced eIF4E and eIF(iso)4E gene segments in watermelon. Analysis of the nucleotide sequences between the ZYMV-resistant watermelon plant introduction PI 595203 (Citrullus lanatus var. lanatus) and the ZYMV-susceptible watermelon cultivar 'New Hampshire Midget' ('NHM') showed the presence of single nucleotide polymorphisms (SNPs). Initial analysis of the identified SNPs in association studies indicated that SNPs in the eIF4E, but not eIF(iso)4E, were closely associated to the phenotype of ZYMV-resistance in 70 F(2) and 114 BC(1R) progenies. Subsequently, we focused our efforts in obtaining the entire genomic sequence of watermelon eIF4E. Three SNPs were identified between PI 595203 and NHM. One of the SNPs (A241C) was in exon 1 and the other two SNPs (C309A and T554G) were in the first intron of the gene. SNP241 which resulted in an amino acid substitution (proline to threonine) was shown to be located in the critical cap recognition and binding area, similar to that of several plant species resistance to potyviruses. Analysis of a cleaved amplified polymorphism sequence (CAPS) marker derived from this SNP in F(2) and BC(1R) populations demonstrated a cosegregation between the CAPS-2 marker and their ZYMV resistance or susceptibility phenotype. When we investigated whether such SNP mutation in the eIF4E was also conserved in several other PIs of C. lanatus var. citroides, we identified a different SNP (A171G) resulting in another amino acid substitution (D71G) from four ZYMV-resistant C. lanatus var. citroides (PI 244018, PI 482261, PI 482299, and PI 482322). Additional CAPS markers were also identified. Availability of all these CAPS markers will enable marker-aided breeding of watermelon for ZYMV resistance.}, number={1}, journal={THEORETICAL AND APPLIED GENETICS}, author={Ling, Kai-Shu and Harris, Karen R. and Meyer, Jenelle D. F. and Levi, Amnon and Guner, Nihat and Wehner, Todd C. and Bendahmane, Abdelhafid and Havey, Michael J.}, year={2009}, month={Dec}, pages={191–200} }
 @article{guner_wehner_2004, title={A fasciated mutant in watermelon}, ISBN={1064-5594}, number={27}, journal={Report (Cucurbit Genetics Cooperative)}, author={Guner, N. and Wehner, T. C.}, year={2004}, pages={30} }
 @article{guner_wehner_2004, title={Accessions having opposite leaf arrangement at the first true leaf in watermelon}, ISBN={1064-5594}, number={27}, journal={Report (Cucurbit Genetics Cooperative)}, author={Guner, N. and Wehner, T. C.}, year={2004}, pages={32} }
 @article{wehner_guner_2004, title={Growth stage, flowering pattern, yield, and harvest date prediction of four types of cucumber tested at 10 planting dates}, ISBN={["90-6605-667-3"]}, ISSN={["0567-7572"]}, DOI={10.17660/actahortic.2004.637.27}, abstractNote={Cucumber (Cucumis sativus) is a major vegetable crop worldwide. Compared with many crops, cucumber reaches harvest stage rapidly. Computer growth models have been developed to help researchers, growers, and processors predict plant development and harvest date. The objective of this study was 1) to study growth and development of cucumber using both days after planting and cumulative heat units (HU) to determine their value in prediction of harvest date for pickling cucumbers grown in North Carolina, and 2) to study vegetative and flowering patterns from planting to harvest. The experiment was a split-plot treatment arrangement in a randomized complete block design with three replications. Plantings were made every week for 10 weeks (30 April through 2 July). Four cultigens were chosen to represent a range of types. Data on plant growth stage and weather conditions were collected daily. Main growth stages were planting (direct seeding), emergence, vine tip over, flowering, and fruit harvest. Heat units were calculated from weather data using a model with the daily maximum air temperature, a base temperature of 15.5°C, and a reducing ceiling of 32°C. ‘Calypso’ was the earliest maturing cultigen, M 21 and Wis. SMR 18 were intermediate, and WI 2757 was the latest. Plantings made early in the season required more days to reach fruiting stage than those made later. Heat units were more stable over planting dates than days after planting. ‘Calypso’ had more branches per plant and more nodes per branch than the dwarf-determinate cultigen M 21. Early yield was correlated with number of branches/plant and nodes/branch. Additional research is needed to improve the heat unit model so that it predicts harvest date accurately regardless of planting date. INTRODUCTION Cucumber (Cucumis sativus) is a major vegetable crop in North Carolina, with the second largest production of pickling cucumber, and the third largest production of slicing cucumber in the U.S. (United States Department of Agriculture, 2001). Cucumber develops rapidly, with a shorter time from planting to harvest than for most crops. However, the number of days to harvest changes with temperature, making it difficult to predict. Computer growth models have been developed for crop production systems, providing a means for organizing what is known about their growth and development. An example of a model that has been used successfully for soybean studies is SOYGRO (Wilkerson et al., 1983; Jones et al., 1991). Prediction of growth stage and harvest date have been used to improve crop management. Uses include scheduling labor and machinery, integrated pest management practices, and timely production for high market prices (Perry and Wehner, 1996). Most cucumber cultivars grown before 1980 were monoecious. In monoecious cultivars, the staminate flowers are produced first (nodes 1 to 9), followed by an alternating staminate-pistillate stage, and finally, a continuous pistillate stage (Shifriss, 1961; Tasdighi and Baker, 1981). Yield is dependent on pollination, since fruits develop after bees pollinate the pistillate flowers, unless the plant is parthenocarpic. Now, most Proc. XXVI IHC – Advances in Vegetable Breeding Eds. J.D. McCreight and E.J. Ryder Acta Hort. 637, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA) 224 cultivars of pickling and slicing cucumber used in the U.S. are gynoecious hybrids. Gynoecious plants usually have a ratio of pistillate to staminate flowers of 9:1 (McMurray and Miller, 1969). Gynoecious cultivars intended for field production are blended with a monoecious hybrid or inbred to provide the pollen necessary for fruit set, with 10 to 15% monoecious plants being optimum (Miller, 1976). Gynoecious hybrid cultivars and mechanical harvesting make harvest prediction for cucumber even more important for harvest scheduling and grower profitability. A heat unit model has been developed for cucumber (Perry et al., 1986; Perry and Wehner, 1990) that predicts harvest date for cucumbers grown under different conditions. Other models (Chen et al., 1975; Haffar and Van Ee, 1990) have been developed to solve additional production problems. The objective of this study was to compare days after planting and cumulative heat units to determine their value in prediction of harvest date for pickling cucumbers grown in North Carolina. Further, we were interested to determine the relationship between yield and vegetative traits such as branch number, node number, and percentage of pistillate nodes. MATERIALS AND METHODS All experiments were conducted at the Horticultural Crops Research Station, Clinton, N.C. Plantings were made every week for 10 weeks (30 April through 2 July). The experiment was a randomized complete block design with three replications and a split plot treatment arrangement. Whole plots were 10 planting dates and subplots were four cultivars and breeding lines (cultigens). The four cultigens ‘Calypso’, M 21, ‘Wis. SMR 18’, and WI 2757 were chosen to represent groups of interest to breeders, including inbreds vs. hybrids, new vs. old releases, anthracnose resistant vs. susceptible, and early vs. late maturity. Plots were seeded on raised, shaped beds in rows 1.5 m apart. Plots were 6 m long separated by 1.5 m alleys at each end and were thinned to 60 plants per plot (64,556 plants/ha). The soil type in the study was a mixture of Norfolk, Orangeburg, and Rains (fine-loamy, siliceous, thermic, Typic Kandiudults) with some Goldsboro (fine-loamy, siliceous, thermic, Aquic Paleudults). Recommended horticultural practices (Schultheis, 1990) were used for all experiments. Fertilizer was incorporated before planting at a rate of 90-39-74 kg/ha (N-P-K), with an additional 34 kg/ha N applied at the vine tip over stage. Curbit (ethalfluralin N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine) was applied for weed control. Irrigation was applied when needed for a total (irrigation plus rainfall) of 25 to 40 mm per week. ‘Sumter’ pollenizer was planted in side rows and end plots to provide additional pollen and border competition for the test plots. No disease problems were observed. Data on plant growth stage and weather conditions were collected daily. Main growth stages were emergence (50% of plants at cotyledon stage), vine tip over (50% of plants had top leaves touching soil), flowering (50% of plants with flowering), and fruit harvest. Harvest stage was further divided into 5, 25, 50, and 75% fruit yield from six harvests. Total yield was the sum of six harvests, and early yield was the sum of the first two harvests. Heat units were calculated from weather data using the method of Perry et al. (1986), which uses the daily maximum air temperature, a base temperature of 15.5°C, and a reducing ceiling of 32°C: If maximum air temperature (Max)≤32°C, then HU=Max-15.5; If maximum air temperature (Max)>32°C, then HU=[32-(Max-32)]-15.5. Vegetative traits were measured at first harvest, including branches/plant, node of branch location, nodes / branch, and number of staminate and pistillate flowers. All plots were harvested when 50-mm-diameter fruit were first observed in the experiment. Plots were harvested twice weekly for three weeks. Fruit were graded as marketable or cull, and weighed to get marketable yield. Marketable yield was highly correlated (r = 0.99) with total yield (marketable + cull), so data on total yield data were not presented in the figures and tables. Early yield was fruit weight in the first two harvests. Data were}, number={637}, journal={ADVANCES IN VEGETABLE BREEDING}, publisher={Leuven, Belgium : International Society for Horticultural Science}, author={Wehner, TC and Guner, N}, year={2004}, pages={223–229} }
 @article{wehner_guner_2004, title={Qualitative genes for use in development of elite watermelon cultivars}, ISBN={1064-5594}, number={27}, journal={Report (Cucurbit Genetics Cooperative)}, author={Wehner, T. C. and Guner, N.}, year={2004}, pages={24} }
 @article{guner_wehner_2004, title={The  genes of watermelon}, volume={39}, number={6}, journal={HortScience}, author={Guner, N. and Wehner, T. C.}, year={2004}, pages={1175–1182} }
 @article{guner_wehner_2003, title={Survey of US land-grant universities for training of plant breeding students}, volume={43}, DOI={10.2135/cropsci2003.1938}, abstractNote={A survey was conducted to identify land‐grant universities in the USA having plant breeding programs, and to determine the number of domestic and international plant breeding students graduating at the M.S. and Ph.D. levels from those programs in 1995 to 2000. A total of 71 U.S. land‐grant universities were identified. There were 409 (53%) Ph.D. and 361 (47%) M.S. degrees awarded. Of the total, 362 (47%) graduates were domestic and 408 (53%) were international. There was no major change in the total number of plant breeding graduates during the 6‐yr period. The largest numbers of plant breeding students were trained in agronomy (crop science) departments, followed by plant breeding departments or groups, horticulture departments, plant science departments, and combined agronomy–horticulture departments. Universities with an average of seven or more graduates per year were University of Wisconsin‐Madison, North Carolina State University, University of Nebraska‐Lincoln, Cornell University, University of Minnesota‐St. Paul, Iowa State University, and Texas A&M University. The downward trend noted in previous surveys has continued to the point where there are only a few universities with large plant breeding programs remaining in each region of the country. If the USA is going to continue its public effort in plant breeding research and graduate student training, sufficient federal and state funding will have to be provided to support at least the current regional centers.}, number={6}, journal={Crop Science}, author={Guner, N. and Wehner, Todd}, year={2003}, pages={1938–1944} }
 @article{guner_strange_wehner_pesic-vanesbroeck_2002, title={Methods for screening watermelon for resistance to papaya ringspot virus type-W}, volume={94}, ISSN={["1879-1018"]}, DOI={10.1016/S0304-4238(02)00007-9}, abstractNote={Papaya ringspot virus-watermelon strain (PRSV-W) affects all agriculturally important species of the Cucurbitaceae, and is of economic interest because of its destructiveness. The objective of this study was to develop a consistent and reliable method to screen watermelon for resistance to PRSV-W. PRSV-W isolates 1637, 1870, 2030, 2038, 2040, 2052, 2169, 2201, 2207, and W-1A were maintained in ‘Gray Zucchini’ squash, and were used in the inoculations. Three experiments were run, a preliminary experiment to determine the important factors involved in disease development, a main experiment to quantify the effects of those factors, and a retest of three cultigens to determine test variability. The experiment was a split-plot treatment arrangement in a randomized complete block design with four replications. Whole plots were growth stage (cotyledon, first true leaf), subplots were pot size (55 or 100 mm), and sub-subplots were the 10 isolates. Plants were rated on a scale of 0–9 for each of three traits: leaf necrosis, mosaic symptoms, and leaf deformation. We found the best method for a screening of the watermelon germplasm collection for resistance to PRSV-W is to grow the seedlings in square, 100 mm diameter pots (or 55 mm diameter pots if uniform germination is expected) and inoculate plants at the first true leaf stage using PRSV-W isolate 2052 and the rub method. Significant differences were obtained (with LSD values of 0.6–1.5) using four replications of five plants per plot, but fewer replicates and plants may be adequate for a large germplasm screening experiment. The method can be used by researchers interested in screening for PRSV-W resistance in watermelon, verifying that resistance, studying its inheritance, and transferring it to elite cultivars.}, number={3-4}, journal={SCIENTIA HORTICULTURAE}, author={Guner, N and Strange, EB and Wehner, TC and Pesic-VanEsbroeck, Z}, year={2002}, month={Jun}, pages={297–307} }
 @article{strange_guner_pesic-vanesbroeck_wehner_2002, title={Screening the watermelon germplasm collection for resistance to papaya ringspot virus type-W}, volume={42}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2002.1324}, abstractNote={Papaya ringspot virus watermelon strain (PRSV-W), formerly watermelon mosaic virus-1, is a major disease of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. The objectives of this study were (i) to screen the USDA watermelon germplasm collection for PRSV-W resistance, (ii) to verify the disease rating for the most resistant and most susceptible accessions, (iii) to determine the number of escapes on the basis of the retest of the germplasm screening test. The experiment was a randomized complete block with five replications and 1275 accessions. 'Charleston Gray' susceptible checks were used to verify that the PRSV-W inoculum was virulent. Enzyme-linked immunosorbent assay (ELISA) was performed after the last rating to determine whether the virus was in the plant tissue. The PI accessions with the highest resistance to PRSV-W that also had resistance to other watermelon viruses (ZYMV, zucchini yellow mosaic virus or WMV, watermelon mosaic virus, formerly watermelon mosaic virus-2) were PI 244018, PI 244019, PI 255137, and PI 482299. The first retest of the most resistant 21 PI accessions showed that there were some escapes that were not resistant to PRSV-W. Of the 21 PI accessions in the retest, seven PI accessions were identified for further testing. Of the 60 resistant PI accessions in the final retest, eight had resistance with a rating of 3.6 or less for the best, average, and maximum ratings: PI 244017 (best over all tests), PI 244019, PI 482342, PI 482318, PI 485583, PI 482379, PI 595203, and PI 244018.}, number={4}, journal={CROP SCIENCE}, author={Strange, EB and Guner, N and Pesic-VanEsbroeck, Z and Wehner, TC}, year={2002}, pages={1324–1330} }